The invention relates to a device for coating granulates and seeds.
Such a device is known from DE 40 36 697 C2 whose disclosure content is hereby fully incorporated in the present invention specification.
Such devices, which are also commonly known as xe2x80x9cdragxc3xa9e making machinesxe2x80x9d, are used for coating granulates and seeds, especially in the pharmaceutical industry, but also in the food industry and especially in the candy industry.
These are relatively large rotating driven drums in which the seeds to be coated are placed. One or more nozzle lips engage in the drum via which, during operation, a coating is distributed over the seeds or granulates rotating in the drum.
A sophisticated air system is required which is responsible for preventing that the seeds, which are usually coated with a sticky coating, will stick together.
Such machines must be thoroughly cleaned after the coating process is completed. Cleaning is difficult as the drum is not easily accessible because it is connected to respective air supplies and covered by a housing.
It is known in the art to clean the drum through respective access openings where spray nozzles are placed in said access openings so as to distribute the cleaning agent in the drum.
However, the known cleaning process is disadvantageous in that the air inlet and air outlet ducts in the drum can be cleaned only with considerable effort or not at all.
Therefore, it is the aim of the invention to configure a device as described above such that it can be cleaned better overall. Especially the air inlet and outlet ducts should be cleaned quickly and highly efficiently.
A substantial feature of the invention is that the air is distributed in the drum by means of an air distribution plate fixed to the front side of the drum disposed opposite a non-rotating air distribution plate fixed to the housing, which is formed such that it can move in axial direction towards and away from the drum and which can be connected to the drum by means of air.
The technical solution offers the considerable advantage that the entire air distribution and removal system is configured such that it can move towards and away from the drum because a non-rotating air distribution plate is provided on the front side of the drum, which can move in axial direction towards and away from the drum.
This is advantageous in that the air distribution plate fixed to the housing can be lifted off of the front side of the drum for cleaning purposes, which, for one, exposes the air ducts leading into the front side of the drum where they can be cleaned very easily and also, the part of the air supply to the drum on the housing is easily accessible and can be quickly inspected and cleaned.
Therefore, such a movable air distribution plate fixed to the housing is also advantageous in that all air supplies close to the drum and on the drum can be visually inspected so as to determine whether any foreign objects or residues from other products remain in the air system. The drum will then not be reloaded for reasons of hygiene. Therefore, inspections and cleaning of the air inlet and outlet ducts, both on the housing and the drum, are considerably improved.
The displacement drive for shifting the air distribution plate fixed to the housing in axial direction can be realized by various different embodiments. According to a preferred embodiment, the displacement drive is achieved by means of several thrust cylinders evenly distributed over the circumference. One side of the thrust cylinder is supported by a buffer fixed to the housing while the other side, for example the piston rod, joins the air distribution plate fixed to the housing.
According to a preferred embodiment, three such thrust cylinders are evenly distributed over the circumference.
Of course, in other embodiments, other axial displacement drives can be used for the air distribution plate, such as an electromagnet, a spindle drive, a linear motor or a hydraulic cylinder.
According to another feature of the invention, which is to be protected separately from the above mentioned axial, movable driven air distribution plate, the air ducts in the drum are also especially easy to clean.
According to said additional feature, each of the ducts in the drum is covered in radial outward direction by means of an air duct cover substantially extending approximately
over the total axial length of the drum and which is also configured such that it can move in a radial direction towards and away from the drum.
The above results in the considerable advantage that by lifting off the air duct covers and possibly swinging them out, the air ducts in the drum can also be made easily accessible.
There are various embodiments for moving the air duct covers, all of which are encompassed by the present inventive idea.
According to a first embodiment of the invention, the air duct covers are configured such that with their respective left and right side mountings on the drum, they can be removed and moved towards the surface area of the drum approximately parallel to said surface area. To this aim, the two opposite mountings are provided with suitable articulated levers. Therefore, by means of operating said articulated levers manually or device-controlled, each air duct cover can be lifted off of the drum in radial direction so as to produce a cleaning gap extending in axial direction of the drum between the drum surface and the removed air duct cover.
Cleaning is achieved in that when the air duct covers are lifted off, the drum with its bottom part dips into a vat filled with cleaning solution disposed underneath the drum. The cleaning solution enters through the above mentioned cleaning gap between the surface area of the drum and the lifted off air duct covers and thus cleans all air ducts in the drum.
According to another, further feature of the invention, the air duct cover can be lifted off not only parallel and in vertical direction with respect to the surface area of the drum, it can additionally (or alone and solely) be configured such that it can swing towards and away from the drum.
Therefore, this means that the respective air duct cover is mounted on the drum so as to swing on one side and it can swing away or towards the drum.
Both possible movements, which means lifting the air duct cover parallel off of the drum and the swinging movement of an air duct cover mounted on one side of the drum so as to swing, are protected separately by the present invention as essential features of the invention.
The air duct cover swinging away fully is advantageous in that the air duct cover is thus swung away completely from the drum and the interior can be visually inspected. It can also be fully removed, i.e. it is mounted on a hinged bearing disposed on one side and can easily be removed.
According to a preferred embodiment, nine air supply openings are evenly distributed over the circumference of the drum, each of which leading into an associated air duct. Consequently, each air duct can be sealed by means of an air duct cover, which, according to the above description, is configured so as to either move in radial direction or swinging on one or both sides with respect to the drum.
Both moving mechanisms, namely the radial movement and the swinging movement, can be combined in one single device.
This is preferably achieved by providing a dual lever mechanism which ensures that the two sides of the air duct cover are evenly lifted off of the drum when a dual lever provided on one side is actuated.
The subject matter of the present invention not only comprises the subject matter of each individual patent claim, it also comprises the combination of the individual patent claims.
All information and features disclosed in the documents, including the abstract, especially the spatial configuration illustrated in the drawings, are claimed as essential to the invention to the extent that they are new compared to the prior art, either individually or combined.